Such a component usually comprises a housing, which has a lower shell and an upper shell and delimits at least one fresh air path, which runs from at least one fresh air inlet of the housing to at least one fresh air outlet of the housing.
In vehicle applications, the fresh air system and the components thereof are usually accommodated inside an engine compartment of the vehicle, which is closed on its upper side with the aid of a bonnet. The installation space available in the engine compartment is utilised as much as possible. It can happen that at least one component of the fresh air system is arranged proximally to the bonnet of the engine compartment. In such an arrangement of the respective fresh air system component directly underneath the engine bonnet, pedestrian protection problems can occur if the fresh air system component is situated in a displacement path provided for the engine bonnet, in which the engine bonnet in intended to give in the event of a pedestrian impact.
In order that no rigid, disruptive contours that increase the risk of injury are formed here in the displacement path of the engine bonnet by fresh air system components arranged tightly under said engine bonnet, it is in principle possible for the housing to be produced from a comparatively flexible plastic. The housing of the respective component thereby has a certain ability to yield, so that a collision of the engine bonnet with the component causes a deformation of the housing, which however does not produce any impermissibly high force peaks owing to the flexible materials used.
However, the use of flexible materials for the production of the housing of such a fresh air system component has acoustic disadvantages. Firstly, pressure waves produced by combustion are always transported in the fresh air that is conducted in the fresh air system. Said pressure waves in particular run counter to the flow direction of the fresh air. Secondly, oscillations and vibrations of the internal combustion engine and of the vehicle are transmitted to the fresh air system. Both the internal pressure pulsation and the oscillations and vibrations can cause the housing of the fresh air system component to oscillate, which can result in undesirable emission of noise into the engine compartment and can also be a high mechanical load on the housing.